The invention relates most immediately to means for serving the relatively elevated gas-flow requirements of a gas-constricted arc nozzle, as shown and described in pending patent applications, U.S. Ser. No. 824,525, filed Jan. 31, 1986, and U.S. Ser. No. 850,690, filed on even date herewith.
Reference is made to said applications for description of such nozzles, and it suffices here to state that it is expected that the gas-constricted arc nozzle will for many applications displace the familiar gas-shielded electric-arc nozzle which has seen widespread use for welding and like operations. Thus, throughout the world, shops utilizing gas metal arc welding (GMAW) apparatus already possess the supporting equipment necessary for operation of their conventional nozzles. Such supporting equipment includes an electric power supply for operation of the arc, wire-feeding mechanism for feeding consumable electrode material to an arc-discharge nozzle, flexible hose (1) for supplying electrical current to a host torch body that is fitted with a particular nozzle configuration and (2) for delivering a flow of shielding gas to the torch body and its nozzle, and a gas-flow on/off control means in the form of a solenoid valve. The solenoid valve is actuated to open condition to supply gas (as from a charged cylinder) to the shroud or multiple-jet configuration which serves the arc-shielding function of the torch.
Although gas-constricted arc nozzles of said patent applications can be fitted to the conventional host-torch body, the existing means of gas supply and the existing solenoid valve are not of sufficient capacity to serve the gas-flow requirements of said gas-constricted arc nozzles; these requirements are for relatively high gas-flow rates, over a relatively wide range of flowing back-pressures, e.g., 10 to 100 psi above atmospheric pressure, depending upon the nozzle configuration and the gas-flow patterns that are desired for different working operations. The obvious solution would be to provide each customer with a replacement solenoid valve, but this would require the customer to partly dismantle his existing equipment in order to install a new solenoid valve, and it would also mean an inventory burden in regard to different solenoid specifications, inter alia due to the variety of local voltages in use throughout the world.